Consuming red meat can increase the chances of breast cancer, a study published in International Journal of Cancer this week revealed. The Sister Study was a US and Puerto Rico-based nationwide prospective cohort study that evaluated environmental and genetic risk factors for breast cancer. The enrollment period was between 2003 and 2009; eligible participants were 35- to 74-year-old women who had no previous diagnosis of breast cancer and are sisters or half-sisters of women diagnosed with breast cancer. It was jointly done by Columbia Mailman School of Public Health, New York, National University of Singapore, National Institute of Environmental Health Sciences and National Cancer Institute, Bethesda.
Under the study, total of 50,884 women completed the extensive baseline enrollment process, which consisted of a comprehensive interview and self-completed questionnaires covering medical and family cancer history as well as lifestyle and demographic characteristics, including diet and a home exam during which height, weight and weight and hip circumference were measured.
The findings revealed that study participants with higher red meat consumption had worse health behaviors overall and stronger family history of breast cancer compared to those with lower red meat consumption. In terms of poultry consumption, study participants with higher poultry consumption had more years of education and had stronger family history compared to those with lower poultry consumption.
“Red meat consumption increased the risk of invasive breast cancer, whereas poultry consumption was associated with reduced risk, particularly for postmenopausal invasive breast cancer. These associations were more pronounced in substitution models, indicating that substituting poultry for red meat decreases breast cancer risk when the total consumption of red meat and poultry is fixed and substituting red meat for poultry increases breast cancer risk when total consumption of red meat and poultry is fixed,” the study said.
Beef, veal, pork, lamb and game meat come under red meat while white meat includes the poultry chicken, turkey, Cornish hens, duck, goose, quail and pheasant/game birds. “An association between red meat and breast cancer may be due to dietary heme iron, fat and N-glycolylneuraminic acid as these compounds found in red meat are indicated to possibly increase tumor formation,” the study said.
The study holds significance in context to India as red meat is a part of diet in Indian households. According to a Lancet study published last year, India has a low survival rate for breast cancer, with only 66.1% women diagnosed with the disease between 2010 and 2014 surviving. According to the Union health ministry, breast cancer ranks as the number one cancer among Indian females with rate as high as 25.8 per 100,000 women and mortality of 12.7 per 100,000 women. According to estimates, at least 17,97,900 women in India may have breast cancer by 2020.
“Breast cancer is the leading cancer among women, not only in India but worldwide. While this observational study doesn’t prove that red meat causes breast cancer or that chicken prevents it, the authors suggest the switch may be worth considering,” said Ravi Mehrotra, Chief Executive Officer (CEO), Indian Cancer Research Consortium –Indian Journal of Medical Research (ICMR).
“Random clinical trials with a very long follow-up to study the relationship between diet and breast cancer are warranted. Other factors that increase the risk of breast cancer are genetics, obesity, tobacco, alcohol consumption, less number of children and absence of breast feeding,” he said.
Researchers at Karolinska Institutet in Sweden have investigated the long-term effect of hormonal therapy in women with the most common types of hormone-sensitive breast cancer. The results, presented in the journal JAMA Oncology, show that the treatment has a protective effect against distant metastatic cancer for both so-called Luminal A and Luminal B breast cancer subtypes, and a long-term effect for women diagnosed with Luminal A cancer.
Estrogen receptor-positive (hormone sensitive) breast cancer is the most common form of breast cancer and means that the tumor grows in response to the female hormone estrogen. Women who develop this form of breast cancer have a long-term risk of distant metastatic spread of the disease and dying from breast cancer. There is however insufficient knowledge of how biological factors in the tumor and hormonal therapy affect this long-term risk.
Researchers at Karolinska Institutet have now investigated the long-term effect of hormonal therapy in women with the two most common types of estrogen receptor-positive breast cancer. The researchers analyzed long-term data with follow-up for at least 20 years for patients in the Stockholm Tamoxifen trial (STO-3) randomised to receive either tamoxifen treatment or no hormonal therapy. In summary, 336 women were diagnosed with so-called Luminal A breast cancer subtype and 126 women with Luminal B subtype.
The results show that patients with Luminal A breast cancer had a relatively small but prolonged risk increase for metastatic cancer, and that tamoxifen treatment significantly reduced this risk for as long as 15 years after diagnosis. Patients with Luminal B subtype were at high risk for metastatic breast cancer during the first five years after diagnosis. In these patients, tamoxifen treatment led to a significantly reduced risk during the first five years, but after that the protective effect of hormonal therapy decreased.
“Our conclusion is that tamoxifen treatment is beneficial for both groups of patients, but that it has a long-term protective effect for patients with Luminal A breast cancer,” says Dr. Linda Lindström, a research group leader at Karolinska Institutet’s Department of Biosciences and Nutrition, who coordinated the study. “Patients with Luminal B breast cancer should also be offered hormonal therapy, and our results show a reduced risk of metastatic disease during the first years when the risk is the highest for these patients. We will now proceed to investigate the long-term benefits of hormonal therapy in patients with Luminal A and Luminal B subtype who have been diagnosed with larger and aggressive tumours with spread to the lymph nodes.”
The study was funded by the Swedish Research Council, Forte, the Gösta Milton Donation Foundation, the California Breast Cancer Research Program Award, Iris, Stig and Gerry Castenbäck’s Foundation for Cancer Research and King Gustaf V’s Jubilee Foundation from Radiumhemmet Research Foundation. Co-author Laura van’t Veer holds a patent for “Mammaprint 70-gene risk signature” and is co-founder, shareholder and part-time employee at Agendia.